# -*- coding: utf-8 -*-
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# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
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#
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from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals
import os
import random
from typing import Iterable
from airflow.models import Connection
from airflow.exceptions import AirflowException
from airflow.utils.db import provide_session
from airflow.utils.log.logging_mixin import LoggingMixin
[docs]CONN_ENV_PREFIX = 'AIRFLOW_CONN_'
[docs]class BaseHook(LoggingMixin):
"""
Abstract base class for hooks, hooks are meant as an interface to
interact with external systems. MySqlHook, HiveHook, PigHook return
object that can handle the connection and interaction to specific
instances of these systems, and expose consistent methods to interact
with them.
"""
def __init__(self, source):
pass
@classmethod
@provide_session
[docs] def _get_connections_from_db(cls, conn_id, session=None):
db = (
session.query(Connection)
.filter(Connection.conn_id == conn_id)
.all()
)
session.expunge_all()
if not db:
raise AirflowException(
"The conn_id `{0}` isn't defined".format(conn_id))
return db
@classmethod
[docs] def _get_connection_from_env(cls, conn_id):
environment_uri = os.environ.get(CONN_ENV_PREFIX + conn_id.upper())
conn = None
if environment_uri:
conn = Connection(conn_id=conn_id, uri=environment_uri)
return conn
@classmethod
[docs] def get_connections(cls, conn_id): # type: (str) -> Iterable[Connection]
conn = cls._get_connection_from_env(conn_id)
if conn:
conns = [conn]
else:
conns = cls._get_connections_from_db(conn_id)
return conns
@classmethod
[docs] def get_connection(cls, conn_id): # type: (str) -> Connection
conn = random.choice(list(cls.get_connections(conn_id)))
if conn.host:
log = LoggingMixin().log
log.info("Using connection to: %s", conn.debug_info())
return conn
@classmethod
[docs] def get_hook(cls, conn_id): # type: (str) -> BaseHook
connection = cls.get_connection(conn_id)
return connection.get_hook()
[docs] def get_conn(self):
raise NotImplementedError()
[docs] def get_records(self, sql):
raise NotImplementedError()
[docs] def get_pandas_df(self, sql):
raise NotImplementedError()
[docs] def run(self, sql):
raise NotImplementedError()